Arrays Introduction | Java Complete Placement Course | Lecture 10

Java - Introduction to Programming

Lecture 10

Arrays In Java

Arrays in Java are like a list of elements of the same type i.e. a list of integers, a list of booleans etc. 

1. Creating an Array (method 1) - with new keyword

int[] marks = new int[3];

marks[0] = 97;

marks[1] = 98;

marks[2] = 95;

2. Creating an Array (method 2)

int[] marks = {98, 97, 95};

3. Taking an array as an input and printing its elements.

import java.util.*;

 

public class Arrays {

   public static void main(String args[]) {

       Scanner sc = new Scanner(System.in);

       int size = sc.nextInt();

       int numbers[] = new int[size];

 

       for(int i=0; i<size; i++) {

           numbers[i] = sc.nextInt();

       }

 

       //print the numbers in array

       for(int i=0; i<arr.length; i++) {

           System.out.print(numbers[i]+" ");

       }

   }

}

 

Homework Problems

1. Take an array of names as input from the user and print them on the screen.

import java.util.*;

 

public class Arrays {

   public static void main(String args[]) {

      Scanner sc = new Scanner(System.in);

      int size = sc.nextInt();

      String names[] = new String[size];

 

      //input

      for(int i=0; i<size; i++) {

          names[i] = sc.next();

      }

     

      //output

       for(int i=0; i<names.length; i++) {

           System.out.println("name " + (i+1) +" is : " + names[i]);

       }

      

   }

}

 

2. Find the maximum & minimum number in an array of integers. 

[HINT : Read about Integer.MIN_VALUE & Integer.MAX_VALUE in Java]

import java.util.*;

 

public class Arrays {

   public static void main(String args[]) {

      Scanner sc = new Scanner(System.in);

      int size = sc.nextInt();

      int numbers[] = new int[size];

 

      //input

      for(int i=0; i<size; i++) {

          numbers[i] = sc.nextInt();

      }

 

      int max = Integer.MIN_VALUE;

      int min = Integer.MAX_VALUE;

     

       for(int i=0; i<numbers.length; i++) {

           if(numbers[i] < min) {

               min = numbers[i];

           }

           if(numbers[i] > max) {

               max = numbers[i];

           }

       }

 

       System.out.println("Largest number is : " + max);

       System.out.println("Smallest number is : " + min);

      

   }

}

 

3. Take an array of numbers as input and check if it is an array sorted in ascending order.

Eg : { 1, 2, 4, 7 } is sorted in ascending order.

       {3, 4, 6, 2} is not sorted in ascending order.

import java.util.*;

 

public class Arrays {

   public static void main(String args[]) {

      Scanner sc = new Scanner(System.in);

      int size = sc.nextInt();

      int numbers[] = new int[size];

 

      //input

      for(int i=0; i<size; i++) {

          numbers[i] = sc.nextInt();

      }

 

      boolean isAscending = true;

     

       for(int i=0; i<numbers.length-1; i++) { // NOTICE numbers.length - 1 as termination condition

           if(numbers[i] > numbers[i+1]) { // This is the condition for descending order

               isAscending = false;

           }

       }

 

       if(isAscending) {

           System.out.println("The array is sorted in ascending order");

       } else {

           System.out.println("The array is not sorted in ascending order");

       }

      

   }

}